1. D. S. Dugdale J.Mech. Phys.Solids, 8 (1960).
2. J.N. Goodier; F. A. Field Fracture of Solids, eds. Drucker and Gilman, Wiley (1963).
3. J. R. Rice‘Plastic Yielding at a Crack Tip’, to appear in Proc . of Intl. Conf. Fracture, Sendai, Japan (1965).
4. J. A. H.Hult; F.A. Mac Intock Ninth Int. Cong.Appl.Mech., 8, Brussels (1956).
5. F. A. McClintock ibid ref. 2.